need help on building seat

so i have a kz750 that im planning on turning into a cafe racer style bike. i live in indiana so this winter i plan on starting on it. i also will be riding me wife every now and then and would like to transfer my stock seat into a 2 up bump seat but have a horrible imagination and need everyones help, ideas ext. i do have have a friend with a welder so if something needs welded he can do it. i want to completly stay away from fiberglass also. heres the pictures of the seat. not my bike btw.

JC Whitney used to sell the seat kit with cover, foam attached, the whole thing for a double seat for the 750B models (I still have it on mine). You can probably find one online. It's a lot easier to buy the whole thing with foam installed designed to drop onto the existing pan. I can't post a picture of mine because my camera is out of town.

i do like that seat although it does really give me the look im looking for.

My butt used to slide around too much on the flat seat. The double seat is way better because your butt locks right into it.